Black High School Graduation Caps. The classic black graduation cap is the unique high school traditional mortarboard cap offered by Gradshop at low prices to honor your high school graduation ceremony. The grad caps are from high quality matte tricot fabric perfect for all high school graduates. The mortarboard measures 9.4"sq, and the headband includes quality elastic at rim for a comfortable fit. Gradshop offers all graduation cap, gowns and has a variety of tassel colors, so order now for low prices for your high school graduation outfit.